399401280 has 280 divisors, whose sum is σ = 1497360480. Its totient is φ = 100776960.

The previous prime is 399401263. The next prime is 399401287. The reversal of 399401280 is 82104993.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399401287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 492075 + ... + 492885.

It is an arithmetic number, because the mean of its divisors is an integer number (5347716).

Almost surely, 2^399401280 is an apocalyptic number.

399401280 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 399401280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (748680240).

399401280 is an abundant number, since it is smaller than the sum of its proper divisors (1097959200).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

399401280 is a wasteful number, since it uses less digits than its factorization.

399401280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 859 (or 840 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 399401280 is about 19985.0263947787. The cubic root of 399401280 is about 736.4384989358.

The spelling of 399401280 in words is "three hundred ninety-nine million, four hundred one thousand, two hundred eighty".